A sensor is a device that senses a specific media and converts the property of that media into a readable value through electrical signal. This type of sensors is also known as transducers. The present invention relates to a sensor for detecting various ranges of pressures, especially low pressures in the range of a few Pascal. Generally there are three different transduction mechanisms used to measure pressure such as piezoresistive, piezoelectric, and capacitive. However, the capacitive method has certain advantages over the other transduction mechanisms, particularly in low-pressure measurement. This is due to the percentage change in capacitance over pressure.
However, there are two major disadvantages in a capacitive pressure sensor such as parasitic capacitance and leakage current between the plates of the capacitor. Parasitic capacitance is the peripheral capacitance outside the main capacitance area. This is caused as a result of the parallel plates being attached at all parts of their respective surface. The leakage current between two plates deteriorates the capacitance and also degrade the resolution and operating frequency range of the sensor. Therefore, these two unwanted parameters are required to be either completely eliminated or substantially reduced in order to have very minimum impact in the sensor performance. Although ideally these two parameters should be zero, however, in reality, there is always some minimal value exist based on the design features and fabrication techniques.
Therefore in light of the above discussion, there is a need to provide an improved design features and fabrication techniques which can eliminate above mentioned disadvantages and produce a capacitive pressure sensor with minimum parasitic capacitance and leakage current.